Unless you have ears that hear things that mere mortals can't, use THHN, Romex, barbed wire, SJOOW, or any other appropriatly sized conductors you have laying around. If the AVERAGE or RMS, but NOT PEAK power of the speaker is less than 300 Watts, I would use nothing larger than 14 or 12 AWG, especially if the run is less 100 feet round trip.

Actually I do know why people want to know if a particular wire can be used for speakers. It's because the schyster snake oil salesmen want you to use theirs and want you to pay big money for it. What Larry says is right on.

A couple of things about speaker wire. Most of the stuff sold in stereo shops is lamp cord and it cannot be installed into the walls of buildings without a raceway because it does not meet the flame spread requirement in many building codes.Most speaker wire is 2 wires running parallel without a twist or a long capacitor and can alter cross over frequencies. The twist in most building approved cables cancels the capacitance and gives a truer cross over performance. Audiophile propaganda usually makes a fuss about oxygen free copper which most electric wires are without the added cost of the wire that makes a fuss about being oxygen free.Stranded wire is best and fine stranded better as it provides more surface area for the higher frequencies which tend to run on the surface of each strand.Solid wire can work but the frequency response can be affected.Generally the cables made to be installed into walls is better than the marketed stuff in electronics store and is often much cheaper too.Audiophile quality is very often so full of BS and marketing Hype to command outrageous prices. Of course if you were to check the hearing of most Audiophiles you'd find their hearing is about as bad as the rest of us.Very few people can hear 20 to 20,000 hz after our teens.

The twist in most building approved cables cancels the capacitance and gives a truer cross over performance... Stranded wire is best and fine stranded better as it provides more surface area for the higher frequencies which tend to run on the surface of each strand... Solid wire can work but the frequency response can be affected.

Most speaker wire is 2 wires running parallel without a twist or a long capacitor and can alter cross over frequencies. The twist in most building approved cables cancels the capacitance and gives a truer cross over performance.

Capacitance is a function of the area of the two conductive surfaces, the spacing between them, and the dielectric material which separates them.

Everything else being equal, how is twisting two wires together supposed to reduce capacitance?

Without dipping too deep into transmission line theory I will say twisted pairs really look more like a capacitor and an inductor, which gets expressed as impedance in ohms. It is not really important at audio frequencies but when you get up in the RF range it is very important (unless your speaker cables are over 9 miles long, one wavelength at 20kz)